T for the continuous crimp development of three-dimensionally crimped synthetic fibers and filaments

ABSTRACT

An equipment for the continuous crimp development of latently crimped fiber tows made from synthetic linear high molecular weight polymers is described, which contains a drawoff device, a guide device, a heating box having slit nozzles and heated walls, which box is mounted at a distance of at least 50 cm in the line of fall below the guide device. By means of the steam used for the crimp development flowing through the walls of the heating box, condensation of steam is avoided. The equipment furthermore contains a horizontally moving conveyor belt, another heating box for the after-setting of the crimped fiber tow, as well as a draw-off device.

lJnited States Patent 1191 Jacob et al.

[111 3,785,017 [451 Jan. 15, 1974 EQUIPMENT FOR THE CONTINUOUS CRlMP DEVELOPMENT OF THREE-DlMENSlONALLY CRlMPED SYNTHETIC FIBERS AND FILAMENTS [75] inventors: Ingolf Jacob; Gert Buttner; Karl Heinrich, all of Bobingen, Germany [73] Assignee: Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Bruning, Frankfurt am Main, Germany [21] Appl. No.: 248,853

[30] Foreign Application Priority Data May 3, 1971 Germany P 212 1 674.0

[52] US. Cl. 28/l.2, 28/72 HR [51] Int. Cl D02g 1/00 .[58] Field of Search 28/l.2, 72.1, 72 HR,

[56] References Cited UNlTED STATES PATENTS T875,021 6/1970 Addington a a1. ..2s/7 HR 3,099,064 7/1963 Haynes 28/72 HR 3,425,107 2/1969 Matsui et al..... 28/l.2 3,644,968 2/1972 Elliott 28/l.2

Primary Examiner-Louis K. Rimrodt Attorney-Arthur G. Connolly et al.

[ 5 7] ABSTRACT a horizontally moving conveyor belt, another heating box for the after-setting of the crimped fiber tow, as well as a draw-off device.

8 Claims, 5 Drawing Figures PAYENTEUJAHSIQH 3.785.017

sum 10F 2 FIG. 1

Pmmium 1 5 1914 3,785,017

SHEET 2 BF 2 FIG. 2 I ll I fi L,- 7 l I l I l B l I I l l l l 1 FIG. 3

FIGA FIG. 5

- ll EQUIPMENT FOR THE CONTINUOUS CRlIMP DEVELOPMENT OF THREE-DIMENSIONALLY CRIMPED SYNTHETIC FIBERS AND FILAMENTS The present invention relates to an equipment for the continuous development of the latent crimp of fiber tows of synthetic linear high molecular weight polymers in accordance with the process of U. S. Pat. 3,710,463.

In this latter process, the latently crimped filaments are drawn, subsequently dried, at a temperature in the range of from 50 to 230C without permitting shrinkage, and, without applying any tension at all to the filament, the crimp is then developed by means of a heat treatment at a temperature in the range of from 60 to 230C, preferably of from 90 to 130C. For developing the crimp, the latently crimped fiber tow is allowed to fall down freely for 1 meter before dropping on the conveyor belt, and the crimp is developed immediately above the conveyor belt in a state of minimum filament tension, for example by means of overheated steam, and subsequently set.

A vertical heating tube is known from British Pat. No. 1,016,100, in which tube the crimp is developed in a temperature range of from 90 to 160C. French Pat. No. 1,579,662 describes the development of crimp by means of a hot gas jet, and subsequent deposit and transport of the filaments on a conveyor belt. According to German Offenlegungsschrift No.'l,8l7,492, the crimp is developed in a cylindrical heatable blowing chamber at a temperature in the range of from 150 to 250C under shrinkage conditions, and according to German Offenlegungsschrift No. 1,660,456, the crimp of a tow of bi-component filaments being free from tension is developed by means of a steam or air jet having a temperature of 200C.

These known processes have been invented either for filaments, so that it is not possible to use them for the development of the crimp of thick fiber tows in order to obtain a uniform crimp over the whole thickness of the tow, or, as in the French patent, the crimp is developed by means of a hot gas jet, which, though rapidly penetrating the tow, causes disarrangement and entanglement of the fibers, an effect which is undesired for the course of the manufacturing process and for the quality of the tow.

It is therefore the object of the present invention to provide a suitable equipment by means of which, in a completely continuous process following the drawing, a three-dimensional crimp of sufficient uniformity over the whole cross-section area of the tow is obtained. An especially important feature of this equipment is the heating box, in which the latently crimped fiber tow is contacted with the heated agent of treatment. In no event, this agent flowing in should disarrange the tow, and thus subject it to uncontrollable forces which disturb the sensitive process of crimp development. The agent should be admitted to the heating box in a rather slow and diffuse manner, but nevertheless in sufficient amounts, so that it will be able to penetrate the whole tow and heat it to the necessary temperature during the relatively short period of its action. It is important that the tow freely falls in vertical direction into the heating box, which is ensured by a special design of the guide device and a certain minimum distance of this guide device from the heating box.

This object is attained by an equipment containing a drawoff device 1, a guide device 2, a heating box 3 mounted in a line-of-fall-distance of at least 50 cm, preferably of at least cm, from guide device 2, and having slit nozzles 4 and heated walls 5, which wall heating avoids condensation of steam on the walls, furthermore a horizontally moving conveyor belt 6, another heating box 7 for the after-setting of the crimped fiber tow, and finally a draw-off device 8.

In a special design of the equipment of the invention, the heated walls 5 are double walls; the hot gas developing the crimp being conducted through the inside space of these walls.

A further special design of the equipment of the invention provides a heating box 3, the maximum height of which being 100 cm, preferably from 5 to 50 cm, the depth from 10 to 25 cm, preferably from 14 to 18 cm, and the width being determined by the equation B [cm] a K [dtex] 10' in which B is the width of heating box 3 and K the thickness of the tow in dtex.

Furthermore, an especially appropriate equipment is as follows; the lower end of heating box 3, on side 9 turned towards the moving direction of conveyor belt 6, is shorter than on side 10 turned off conveyor belt 6; side 9 thus ends at a distance of from 5 to 20 cm, preferably from 10 to 15 cm, above conveyor belt 6, its lower part being bent to an angle up to 90 in the moving direction of conveyor belt 6 and having a nozzle 4 with blowing device directed towards conveyor belt 6.

Moreover, nozzles '4 preferably are concentric double nozzles, the slits of which are staggered by C.

Preferably, the outer slits of nozzles 4 are closed by a wire cloth having preferably from 2,000 to 6,000 meshes per cm In detail, the cited devices may be of a design as follows: guide device 2 is preferably a bar godet (FIG. 1); the 16 bars of which, for example, having a diameter of 30 mm, are attached with their ends at the rim of 2 circular disks having each a diameter of 40 cm. Thus, larger surfaces on which the steam may condense are avoided, and it is ensured that the tow touches the guide device only at a few spots, so that there is no danger of adhesion of single filaments.

In the dispoisition of the equipment as provided by this invention, the distance between guide device 2 and conveyor belt 6 is of special importance: in order to ensure a reliable run-off of the tension-free, slightly crimped tow, it is necessary to subject it to the load of at least 1 m of tow at the spot where it shall leave the bar godet and fall down.

The behavior of tow movement on guide device 2 will become the more favorable the greater the falling length of the tow from this guide device to conveyor belt 6.

Also the proper distance between the heating box and the conveyor belt is an important feature of the present invention.

In order to obtain an optimum crimp, it must be adjusted in such a manner that the heat convection to the tow by blowing which is necessary to ensure a favorable course of the process is realized at the moment of minimum tensile stress. At the same time, a thorough heating of the fiber tow must be ensured. Therefore, that part of the heating box in which the latently crimped fiber tow is contacted with the heat transferring agent,

for example steam, which develops the crimp, should be situated 50 cm above the con-veyor belt at the utmost, preferably 25 cm or less.

In certain cases it may be advantageous to preheat the tow before it enters the heating box for crimp development. A special design of the heating box therefore provides hot air nozzles for preheating the tow in the upper part thereof.

The equipment of the invention with the cited distances of the substantial devices from each other ensures that the crimp is developed at a moment at which the tow is in the optimum state for the crimp, i.e., nearly without any tension.

90 (FIG. 5) with respect to its original direction. In this now horizontal part of the heating box wall, an additional steam nozzle is preferably embedded, through which steam is vertically blown from above onto the tow which is deposited on the conveyor belt immediately below this nozzle. Here, the crimp development of the fully tension-free tow is completed.

The nozzles through which steam is introduced into the space of treatment are preferably slit nozzles having a width of from 0.5 to mm, preferably from 3 to 6 mm. An especially favorable design of the device provides concentric double nozzles the slits of which are When the tow enters the heating box, it still has the slight tension established by the dead weight of the piece of tow between the upper end of the heating box and the conveyor belt. If this tow was not subjected to any other force, this tension would continue diminishing with the progressive approach of the tow to the conveyor belt and be about zero at the moment of striking the belt. In reality, the zero value is already reached before, since the tow is somewhat stuffed. The tow, therefore, has the tension which is ideal for the crimp development just when passing through the heating box, where, while maintaining the proper distances, most favorable conditions for the crimp development are present.

The heating box for developing the crimp is designed as rectangular double wall box (FIG. 2), the side walls of which contain embedded nozzles'through which a heat transferring agent is contacted with the fiber tow. FIG. 3 is a top view of this device of the invention, FIGS. 4 and 5 are side views of it. No disturbing water of condensation can settle on the inside walls. According to the invention, this is achieved by heating the double wall with steam having the same temperature as the steam used for developing the crimp, for example 100C. By this step, condensation of steam is avoided which otherwise would cause the filaments of the practically tension-free tow to adhere to the wall and thus to stop the passage of the tow through the steam box. A certain determined ratio for the measures of the inside space of the steam box through which the fiber tow must pass has proved to be advantageous: the narrow face A of the inside space (FIG. 2) should be from 10 to 25 cm, preferably from 14 to 18 cm, so that a good penetration of the tow by the steam is ensured. The large face B should be adapted to the thickness of the tow and not be inferior to the amount of the following equation:

B [cm] a K [dtex] lo in which B is the length of the inner edge of the heating box and K the thickness of the tow in dtex.

For a fiber tow of 400 000 dtex, for example, a heating box having an inside width of at least 40cm is used. The nozzles thorugh which the steam is introduced into the box are embedded in the large faces.

The height of the box should not substantially exceed 100 cm, but be preferably from 5 to 50 cm.

Preferably, the side of the heating box which is turned to the conveyor belt in its moving direction may be shorter than the other one and end from 5 to 20 cm, preferably from 10 to l5 cm, above the conveyor belt (FIG. 4). An especially favorable design of the device provides that the last part of this wall of the heating box is bent in such a manner as to form an angle of up to staggered by 180.

The development of a latent crimp of a fiber tow is a very sensitive process which requires utmost care. It proved to be advantageous for the development of a high quality crimp to introduce the agent of treatment acting as heat transmitter in a form as diffuse as possible into the heating box. By no means should it be directed onto the tow in a powerful jet, but it should slowly flow in. The steam is advantageously turbulent within small areas, thus ensuring a rapid and uniform heating also of thick tows.

Therefore, a very advantageous design of the device provides the nozzles to be covered with a wire cloth having preferably from 2,000 to 6,000 meshes per cm Such a wire cloth causes the steam to emerge from a multitude of little orifices, and thus the intended turbulence effect to occur within very small areas, which is important for a uniform penetration of thick fiber tows. A too high speed of the steam flow would prevent such a turbulence effect. The speed of the steam flow should therefore be below 15 m/sec, preferably below 5 m/sec. On the other hand, a sufficient amount of steam must be supplied in order to heat the tow. This is achieved by dimensioning the total surface of the nozzles as large as possible. By a combination of large slit nozzles with wire cloth cover it is possible to convey very much steam into the space of treatment within the given unit of time without disarranging the tow and thus disturbing the sensitive crimp development process.

The speed of the conveyor belt running horizontally below the heating box is adapted to the feed of the tow in such a manner that, considering the very important shrinkage in length occurring during the crimp development, the tow is deposited on the conveyor belt without tension and with only a feeble frill.

In a preferred embodiment of the process of our copending application, Ser. No. 41051/70, the subsequent setting of the crimp is carried out with hot air. It is especially favorable to allow the tow to let off the steam from the crimp development zone as completely as possible before it enters the setting zone. Therefore, the distance between the heating box and the setting oven should be from 1 to 2 m, which distance enables the conveyed tow to let off the steam carried along without cooling too much; the time being from 3 to 10 seconds, preferably from 4 to 5 seconds. Thus, the tow arrives at the setting oven in a dry and preheated state. Setting is carried out at a temperature in the range of from to 210C, preferably from to 180C.

The high temperature in the setting oven causes high shrinkage of the highly crimped monofilaments. This shrinkage, as well as the pronounced three-dimensional crimp, cause adhesion of the fiber tow on the conveyor belt. Therefore, it is necessary to take off the tow from the conveyor belt in an upward direction by means of a pair of rollers before a subsequent further processing.

As compared to the devices known so far, the combination of devices in accordance with the invention has the advantage of allowing a heat treatment of a tensionfree tow which enables the development of crimp also at very feeble crimp forces, even in the case where a considerable shrinkage in length of the tow amounting to more than 50 percent goes along with the crimp process. In connection with a conventional drawing equipment and a setting oven of known design, the combination of devices in accordance with the present invention allows the fully continuous manufacture of helically crimped filaments or fibers from the correspondent undrawn spinning material.

The following example illustrates the invention.

EXAMPLE According to Belgian Pat. No. 708,919, corresponding to US. Pat. No. 3,480,709 an asymmetrically cooled spinning tow having a titer of 400,000 dtex is manufactured. This latently crimped tow is brightened, drawn and dried according to Example 1 of our copending application, Ser. No. 41051/70. The dried tow is drawn off at a speed of 55 m/min and conducted to a bar godet having a diameter of 40 cm, from where it is allowed to fall down vertically for 120 cm onto a conveyor belt. In the space of the last 60 cm before striking this coneyor belt, the tow passes through the double wall heating box which is heated to 100C by means of steam. This inside dimensions of the box are the following:

height 55 cm width 60 cm depth 16 cm Steam of 100C is blown onto the tow via 6 slit nozzles having a length of 60 cm, thus developing a threedimensional crimp. The crimped tow is deposited on the conveyor belt which is running at a speed of m/min, and is so conveyed into a heated setting chamber, in which it is heated for 90 seconds to 150C by means of hot air in order to set the crimp.

What is claimed is: I

1. An equipment for the continuous development of the latent crimp and for setting the developed crimp of fiber tows made from synthetic linear high molecular weight polymers which comprises a draw-off device (1), a guide device (2), a heating box (3) mounted in a line-of-fall-distance of at least 50cm, preferably of at least cm, from guide device (2), and having slit nozzles (4) and heated walls (5), which wall heating avoids condensation of steam on the walls, furthermore a horizontally moving conveyor belt (6), another heating box (7) for the after-setting of the crimped fiber tow, and a draw-off device (8).

2. An equipment as claimed in claim 1, wherein the heated walls (5) are double walls; the hot gas developing the crimp being conducted through the inside space of these walls.

3. An equipment as claimed in claim 1, wherein a heating box (3) is used, the maximum height of which being 100 cm, the depth from 10 to 25 cm, and the width being determined by the equation in which B is the width of heating box (3) and K the thickness of the tow in dtex.

4. The equipment of claim 3, wherein heating box (3) has a height of from 5 to 50 cm and a depth of from 14 to 18 cm.

5. An equipment as claimed in claim 1, wherein the lower end of heating box (3), on its side (9) turned towards the moving direction of conveyor belt (6), is shorter than on side (10) turned off conveyor belt (6); side (9) thus ends at a distance of from 5 to 20 cm, preferably from 10 to 15 cm, above conveyor belt (6), its lower part being bent to an angle up to 90 in the moving direction of conveyor belt (6) and having a nozzle (4) with blowing device directed toward conveyor belt (6).

6. An equipment as claimed in claim 1, wherein nozzles (4) are concentric double nozzles, the slits of which being staggered by 7. An equipment as claimed in claim 1, wherein the outer slits of nozzles (4) are covered with a wire cloth.

8. The equipment of claim 7, wherein the wire cloth has from 2,000 to 6,000 meshes per cm 

1. An equipment for the continuous development of the latent crimp and for setting the developed crimp of fiber tows made from synthetic linear high molecular weight polymers which comprises a draw-off device (1), a guide device (2), a heating box (3) mounted in a line-of-fall-distance of at least 50cm, preferably of at least 150 cm, from guide device (2), and having slit nozzles (4) and heated walls (5), which wall heating avoids condensation of steam on the walls, furthermore a horizontally moving conveyor belt (6), another heating box (7) for the aftersetting of the crimped fiber tow, and a draw-off device (8).
 2. An equipment as claimed in claim 1, wherein the heated walls (5) are double walls; the hot gas developing the crimp being conducted through the inside space of these walls.
 3. An equipment as claimed in claim 1, wherein a heating box (3) is used, the maximum height of which being 100 cm, the depth from 10 to 25 cm, and the width being determined by the equation B (cm) > or = K (dtex) . 1o 4 in which B is the width of heating box (3) and K the thickness of the tow in dtex.
 4. The equipment of claim 3, wherein heating box (3) has a height of from 5 to 50 cm and a depth of from 14 to 18 cm.
 5. An equipment as claimed in claim 1, wherein the lower end of heating box (3), on its side (9) turned towards the moving direction of conveyor belt (6), is shorter than on side (10) turned off conveyor belt (6); side (9) thus ends at a distance of from 5 to 20 cm, preferably from 10 to 15 cm, above conveyor belt (6), its lower part being bent to an angle up to 90* in the moving direction of conveyor belt (6) and having a nozzle (4) with blowing device directed toward conveyor belt (6).
 6. An equipment as claimed in claim 1, wherein nozzles (4) are concentric double nozzles, the slits of which being staggered by 180*.
 7. An equipment as claimed in claim 1, wherein the outer slits of nozzles (4) are covered with a wire cloth.
 8. The equipment of claim 7, wherein the wire cloth has from 2, 000 to 6,000 meshes per cm2. 